javascript设计模式-掺元类

有一种重用代码的方法不需要用到严格的继承。如果想把一个函数用到多个类中，可以通过扩充的方式让这些类共享该函数。其实际做法大大体为：先创建一个包含各种通用方法的类，然后再用它扩充其他的类。这种方式就叫做掺元类。

 function augment(receivingClass,givingClass){
     if(arguments.length > 2){
         for(var i= 2, len = arguments.length;i<len;i++){
             receivingClass.prototype[arguments[i]] = givingClass.prototype[arguments[i]];
         }
     }else{
         for(var methodName in givingClass.prototype){
             if(!receivingClass.prototype[methodName]){
                 receivingClass.prototype[methodName] = givingClass.prototype[methodName];
             }
         }
     }
 }

 function Author(name,books){
     this.name = name;
     this.books = books;
 }
 Author.prototype.getBooks = function(){
     return this.books;
 }

 var MiXin = function(){};
 MiXin.prototype = {
     serialize:function(){
         var output = [];
         for(key in this){
             output.push(key + ":" + this[key]);
         }
         return output.join(", ");
     }
 }
 augment(Author,MiXin);
 var author = new Author("zap","读书笔记");
 console.log(author.serialize());